The present invention relates primarily to pressure fluid cleaning devices which are commonly known as pressure "guns" or "wands" used extensively in the car wash industry with fluid pressures up to approximately 2,000 psi as desired.
In the vehicle cleaning industry, and more particularly in the car wash industry, the trend has been toward increased use of self-service facilities wherein the customer, generally unfamiliar with cleaning equipment, is expected to operate the relatively high pressure fluid cleaning systems, i.e., water jets and the like. Prior art constant spray fluid pressure cleaning devices have the disadvantage of the danger involved in accidental dropping of the wand, known as "flying wand". The reaction force of the high pressure jet stream would result in driving the gun or wand out of control when released, causing damage to the car finish and/or user.
Prior art pressure fluid cleaning devices with on-off control have their own set of disadvantages, in that they have been relatively sophisticated or complicated devices. The expensive and complex valving and hand controlled apparatus provided were generally unsuitable for the unskilled user. Consequently, the possibility of damage and malfunction through misuse was always a concern. Other problems resulted from the rapid increase and decrease in head pressure on the pump system when the "on-off" unloader or regulator valve was operated. The result of "on-off" high pressure valve operation, of course, is rapid damage to cups and seals in the fluid pump system.